The availability of light is a major factor in the ability to grow plants in greenhouse or hydroponic applications. Typically, very strong lights, such as 1000 watt bulbs are used for these applications. It is desirable to remove heat from the vicinity of these bulbs in order to avoid damage to plants.
The intensity of light on a given surface area drops by the square of the distance from the light source. It is desirable to place the light source close to the plant in order to direct light efficiently to the plant. The strong lights generate large amounts of heat that can damage the plants. Therefore it is usually necessary to provide a cooling device for the bulbs to remove heat so that the bulbs may be placed in reasonable proximity to the plants.
The prior art includes air cooled and water cooled devices.
Hydro-Coil
The Hydro-Coil is a handcrafted a water cooled tubular glass coil made from high temperature borosilicate glass. It is fitted over a High Intensity Discharge (HID) lamp. In operation, water is pumped through the vessel. The water absorbs the radiant heat emitted by the lamp. The retail price for the coil is about $390.
The device is typically used in combination with a reservoir kit such as a 20 Gallon reservoir, a submersible pump, and ½″ tubing. A water chiller may be added to obtain additional cooling.
U.S. Pat. No. 5,147,130
U.S. Pat. No. 5,147,130 issued to Watanuki on Sep. 15, 1992 for “Cooling liquid recirculation system for light source unit” describes a cooling liquid recirculation system with walls of transparent jacket tubes for cooling a mercury-vapor lamp, The jacket tubes are provided separately from the lamp, and are formed in optical filters to decrease the temperature of an object to be illuminated. A recirculation unit of cooling liquid for recirculation of the jacket tubes is connected through an elastic duct to a light source unit such as a mercury-vapor lamp. These components are movable for practical use.
U.S. Pat. No. 5,504,666
U.S. Pat. No. 5,504,666 issued to Carmichael on Apr. 2, 1996 for “Light bulb cooling jacket and heat dissipation system” describes a light bulb cooling jacket which is adapted to confine a light bulb in a space through which cooling liquid, such as water, may be circulated. The light bulb cooling jacket includes a shell having a rim, the rim defining an opening in the shell. A stopper fits in the opening in the shell and seals against the rim of the shell. The 5 stopper has an aperture in it. The aperture is adapted to receive a portion of a light bulb, which is held and sealed in place in the aperture. The means employed to hold the bulb in place is adapted to engage a generally cylindrical portion of the light bulb, such as the neck of a standard 1000 W bulb. An important characteristic of the invention that follows from this construction is that the light bulb cooling jacket may be used with a variety of standard high intensity light bulbs. Ports are provided in the stopper for introducing and withdrawing cooling liquid from the 10 space enclosed by the shell and the stopper.
U.S. Pat. No. 6,595,662
U.S. Pat. No. 6,595,662 issued to Wardenburg on Jul. 22, 2003 for “Double-walled grow light housing with air flow cooling system” describes a grow light having an exterior shell with an air inlet and a hot air exhaust outlet, and a specular interior insertable into the shell. The sides of the specular insert are spaced apart from the walls of the shell so as to form a double-walled housing having air cooling chambers and vents which facilitate the movement and exhaust of air heated by high intensity light bulbs.